Sorry, I don't buy it. Maybe I'm a little biased based on past events, but any company that "reminds" someone like that is asking for it. They should have a very clear, flexible policy that claims rights to only work done on company time and/or with company resources. Under no circumstance should the company claim rights to all work done by an employee. It creates a very hostile environment, and is also a very, very stupid business move as it will drive away a great number of highly skilled potential employees.
Even if they convinced an employee to sign such a contract, they should have the common sense to allow them to continue work on projects that are:
- Not closely related to work being done at the company
- Not using company resources and
- Especially not when they provide no financial benefit to the company.
Having employees write modules for CPAN and helping out other programmers in their spare time should be greatly encouraged. Would you rather your programmers just sat at home and played video games? Contributing to Open Source projects is a great way for employees to further develop their skills and improve your company's public image, all at no cost to you. Discouraging employees from doing so results in a very negative situation where everyone loses.
This is a prime example of a very ignorant company shooting itself in the foot. I hope they take steps to patch it up soon.